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65 lines
2.2 KiB
65 lines
2.2 KiB
From e9ab9e04ed76ef06b4ba9a30b3724ca563fdf1fa Mon Sep 17 00:00:00 2001
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From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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Date: Mon, 2 Nov 2015 18:13:27 -0500
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Subject: [PATCH v2 XSA157 5/5] xen/pciback: Don't allow MSI-X ops if
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PCI_COMMAND_MEMORY is not set.
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commit f598282f51 ("PCI: Fix the NIU MSI-X problem in a better way")
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teaches us that dealing with MSI-X can be troublesome.
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Further checks in the MSI-X architecture shows that if the
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PCI_COMMAND_MEMORY bit is turned of in the PCI_COMMAND we
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may not be able to access the BAR (since they are memory regions).
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Since the MSI-X tables are located in there.. that can lead
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to us causing PCIe errors. Inhibit us performing any
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operation on the MSI-X unless the MEMORY bit is set.
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Note that Xen hypervisor with:
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"x86/MSI-X: access MSI-X table only after having enabled MSI-X"
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will return:
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xen_pciback: 0000:0a:00.1: error -6 enabling MSI-X for guest 3!
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When the generic MSI code tries to setup the PIRQ without
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MEMORY bit set. Which means with later versions of Xen
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(4.6) this patch is not neccessary.
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This is part of XSA-157
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CC: stable@vger.kernel.org
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Reviewed-by: Jan Beulich <jbeulich@suse.com>
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Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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---
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drivers/xen/xen-pciback/pciback_ops.c | 8 +++++++-
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1 file changed, 7 insertions(+), 1 deletion(-)
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diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
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index 648c09c..edb9357 100644
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--- a/drivers/xen/xen-pciback/pciback_ops.c
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+++ b/drivers/xen/xen-pciback/pciback_ops.c
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@@ -212,6 +212,7 @@ int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
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struct xen_pcibk_dev_data *dev_data;
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int i, result;
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struct msix_entry *entries;
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+ u16 cmd;
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if (unlikely(verbose_request))
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printk(KERN_DEBUG DRV_NAME ": %s: enable MSI-X\n",
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@@ -223,7 +224,12 @@ int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
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if (dev->msix_enabled)
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return -EALREADY;
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- if (dev->msi_enabled)
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+ /*
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+ * PCI_COMMAND_MEMORY must be enabled, otherwise we may not be able
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+ * to access the BARs where the MSI-X entries reside.
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+ */
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+ pci_read_config_word(dev, PCI_COMMAND, &cmd);
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+ if (dev->msi_enabled || !(cmd & PCI_COMMAND_MEMORY))
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return -ENXIO;
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entries = kmalloc(op->value * sizeof(*entries), GFP_KERNEL);
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--
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2.1.0
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